Why Use a Better Microscope When You Can Just Make Cells Bigger?

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Diapers are revolutionizing how scientists examine brains under the microscope by expanding the brain cells themselves, making them easier to see.

The technology, called expansion microscopy, uses water absorbent polymers to physically expand brain samples. It’s an exotic use for a very common material that’s used in diapers to keep babies dry. With it, scientists can obtain detailed images of tissue samples that may otherwise be too small or take too long to scan. And, because the focus is on the tissue rather than the lens, it could make certain research more affordable because scientists won’t have to splurge for a new microscope.

By expanding brain cells such as these, scientists can study them in higher detail without needing a more powerful microscope.

The inspiration for the technique was simple, said Paul Tillberg, a research assistant in Edward Boyden’s lab at MIT and an author of the study, in a video: “Wouldn’t it be great it if we could just expand the tissue?” he said. “You could see so much more detail by doing that.”

Carolyn Johnson, reporting for the Boston Globe, explains how the procedure works:

Researchers first attach glowing tags to the particular molecules they are interested in seeing — for example, they might choose receptors found on the surface of a particular kind of cell. Next, they add the building blocks of a polymer that is more commonly found in baby diapers, used to absorb moisture.

A substance that Boyden compares to meat tenderizer is used to strip away molecules that could constrain the tissue from expanding. Last, they add water, which is absorbed by the polymer and swells up.

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The swollen tissues can then be examined under microscopes commonly found in research facilities.

The paper on expansion microscopy, published online last week in the journal Science, adds to the body of work striving to understand the connections in the brain that underlie consciousness, health, and disease. “What’s cool about this is that you actually can start to navigate brain circuits,” Boyden said in a video. “You can scan chunks of brain tissue, but with nanoscale precision.”